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Medial Collateral (MCL) Ligament Injury of the Knee, Damaged Knee Ligament, Knee Ligament Sprain

The medial ligament is one of the most commonly damaged knee structures in sports and activities. The knee is vulnerable to the forces we (and other people) put upon our knees as we run, twist, turn and jump, often leading to knee ligament strains, sprains or ruptures.

Luckily the medial knee ligament has a good blood supply and usually heals very well, but it is worth getting advice from a physiotherapist or other sports therapist to ensure you get the best treatment and rehabilitation. That way you will heal up best and can go back to doing what you did before.

The Medial Ligament of the Knee (MCL)

As you can see from the diagram below, the medial ligament runs from the lower part of the inside of the femur (thigh bone) to the upper part of the tibia (shin bone), holding the inside of the knee together. This stops the knee from developing an unhelpful degree of knock-knee position, in other words it, along with the other three main ligaments, maintains the stability of the knee.

It is a big structure and is very strong, with a good blood supply. It allows a backwards and forwards movement of the knee, restricting the sideways bend and contributing to preventing the knee from going further than straight. It stops the inside part of the knee joint widening under stress.

MCL injuries are usually caused by physical force applied to the outside of the knee, such as somebody tackling or colliding with the outside of the leg.
The injured person feels a severe, sharp pain on the inside of the knee. Moving the knee and walking on it may be painful, with swelling developing over hours or by the next morning.

The Severity of Medial Ligament Injury

Injury to a ligament is graded to indicate how severe the damage is. Treatment differs for each grade

Grade 1

  • There is mild tenderness on the inside of the knee over the ligament.
  • Typically there may be no swelling.
  • If the medial ligament is stressed by applying a force to the outside of the knee (a typical ligament test done by therapists and doctors at about 30 degrees bend) there is some pain but there is no abnormal movement or joint looseness (laxity).

This means the ligament has been strained but that it still doing its job well.

Grade 2

  • There is significant tenderness on the inside of the knee over the medial ligament.
  • The knee will have some swelling (effusion) and there may be swelling over the inside of the knee also.
  • When the knee is tested as above, there is pain and an obvious feeling of some laxity in the joint. This means the joint opens up on the inside and there is an abnormally large amount of movement. However, the looseness is not complete; it stops at some point, indicating that the ligament, though damaged, is intact.

Grade 3

  • Pain can vary. It can be severe or less than for the grade 2 sprain.
  • Swelling (effusion) will occur in the knee over hours or by next morning.
  • When the knee is stress tested the inside of the joint widens significantly. The tester can feel no resistance to the opening movement as the knee moves into an abnormal position.
  • The person complains commonly of having a very wobbly or unstable knee.

This indicates that there is a complete rupture of the medial ligament.

A severe medial ligament sprain or rupture may not occur on its own; other structures such as the anterior cruciate ligament and the menisci may be damaged at the same time.

side view of knee anatomy   

Management of Medial Ligament Injury

The MCL is a large structure and has a good blood supply. Because of this, unlike most of the knee ligaments it has an excellent ability to heal. In most cases, isolated medial ligament injuries heal without significant long-term problems.

Orthopaedic surgeons have varying opinions about how best to treat medial ligament injuries, but most agree with allowing them to heal without surgery.

Diagnosis and treatment of acute laxity (looseness) of the inner side of the knee is vital as soon as possible. If taken early, a one week course of anti-inflammatory drugs may improve the healing ability of the ligament by up to 50%.

The knee is not usually immobilised in a plaster cylinder but a long-leg, hinged brace is often used for 4 to 6 weeks. The range of motion of the knee is often kept restricted for a while, because full bend or full straightening of the knee pulls on the medial ligament.

Full weight-bearing on the leg is usually allowed, and the person sent to physiotherapy for rehabilitation.

Treatment for Medial Ligament Injuries of the Knee

All acute injuries vary but most are managed using the PRICE system.
Typical treatment recommendations:

  • Grade 1 injury to the ligament. Compression, elevation, and cold therapy (cryotherapy) are standard treatments. Compression may be the most important, limiting a disabling build up of swelling in the knee. Ice or other cold therapy can be used and crutches may be useful for a short time, with the person allowed to weight bear as they can on the leg.
  • Grade 2 injury. As the ligament has been damaged enough to allow some abnormalmovement of the joint,a hinged knee brace can be used to protect the joint from going into the damaged range. The brace is usually locked to prevent the knee straightening more than 20 to 30 degrees from straight but allows full bend. The person may be allowed to bear weight as tolerated, with crutches initially.
  • Grade 3 injury.Due to the severity of the injury, the person may be non weight-bearing (NWB) on the leg initially. A hinged braced is important to prevent the abnormal joint movement which might occur without protection.

MCL injuries are best treated with early range of motion (ROM) and strengthening of the muscles which surround and stabilise the knee. Most people get back to their previous levels of activity or sport. If there is a very slow or difficult progress towards normality, anterior cruciate ligament damage or a meniscal tear should be considered.


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